Coil of continuous elongated material

ABSTRACT

A coil made of a continuous piece of elongated material such as tubing, prebent into pancake-like spirals called radial layers, each radial layer made up of several concentric and coplanar convolutions, with several radial layers stacked axially, and method and apparatus for making such coils. The material is bent prior to coiling at predetermined bending radii which are different for different convolutions within a radial layer. One or more of the convolutions within each radial layer may be bent at constant bending radius; the rest may be bent at gradually changing radii. The bending radius is controlled by an electric and hydraulic network employing both timed and feedback controls. The coil may be built either upwardly, with the most recently made radial layer always at the bottom of the coil, or it can be built downwardly, with the most recently made radial layer always on the top of the coil.

United States Patent [191 Meyfarth et al.

[ COIL OF CONTINUOUS ELONGATED MATERIAL [75] Inventors: Herbert J.Meyfarth, Cleveland,

Ohio; John J. Crosby, Cambria Heights, NY.

[73] Assignee: Republic Steel Corporation,

Cleveland, Ohio [22] Filed: June 24, 1971 [21] Appl. No.: 156,457

Related US. Application Data [62] Division of Ser. No. 823,764, May 12,1969.

- 242/83 [51] Int. Cl B65h 55/00, B2lc 47/00 [58] Field of Search242/159, 82, 83; 72/138 [56] References Cited UNITED STATES PATENTS918,235 4/1909 Wendtland 242/83 1,992,430 2/1935 Johnson 242/833,145,760 8/1964 I Brautigam 72/138 3,236,467 2/1966 Short et al. 242/83[451 Jan. 15,1974

3,337,154 8/1967 Smith, Jr. et a1. 242/83 3,445,077 5/1969 Cole et a1.242/83 Primary Examiner-Stanley N. Gilreath Attorney-Robert P. Wright eta1.

[ 5 7 ABSTRACT A coil made of a continuous piece of elongated materialsuch as tubing, prebent into pancake-like spirals called radial layers,each radial layer made up of several concentric and coplanarconvolutions, with several radial layers stacked axially, and method andapparatus for making such coils.

The material is bent prior to coiling at predetermined bending radiiwhich are different for different convolutions within a radial layer.One or more of the convolutions within each radial layer may be bent atconstant bending radius; the rest may be bent at gradually changingradii. The bending radius is controlled by an electric and hydraulicnetwork employing both timed and feedback controls. The coil may bebuilt either upwardly with the most recently made radial layer always atthe bottom of the coil, or it can be built downwardly, with the mostrecently made radial layer always on the top of the coil.

5 Claims, 11 Drawing Figures PATENTED 39785587 summw T fi-Ylr 20PATENTED 1 5 1 saw 2 40F 5 PATENTEBJAH 1 5 I974 sum u or 5 WHWW/ COIL OFCONTINUOUS ELONGATED MATERIAL CROSS REFERENCE TO RELATED APPLICATIONThis application is a divison of my co-pending Application Ser. No.823,764, filed May 12 1969 for COIL- ING METHOD AND APPARATUS.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention isin the field of coiling and uncoiling continuous elongated pieces ofrigid material such as tubing, rod, strip and the like which retaintheir shape unless prebent into a different shape.

It is sometimes desirable to coil several hundred feet of large diametersteel tubing which must be prebent in order to stay in coil form.Generally used known methods of coiling are unsatisfactory, since theyinvolve no prebending; hence a coil will not retain its shape unlessseverely constrained at all times. In the case of steel tubing used forgas mains, for example, it is desirable to have a coil which has minimaldimensions, to facilitate transportation, but contains maximum length oftubing to reduce the number of joints in laying long conduits, and iseasily handled in coil form especially in connection with uncoiling inthe field.

2. Prior Art Coils of the general arrangement described in thisapplication have been made in the past as exemplified by the U.S. Patentto Sibley, No. 2,723,807 and the U.S. Patent to Smith, Jr. et al., No.3,337,154. In both patents the coiled material is bent at the point ofcoiling, with the essential help of either the coil spool or the alreadycoiled material. The material is not bent prior to coiling.

This prior art method may be useful for highly ductile materials such assoft copper, or for other materials which exhibit very weak springcharacteristics. It could not be used for materials such as steel,because steel must be prebent in order to stay in coil form. Even if theyield point of the material could be exceeded by forcing it into a coilsimilar to that of the above patents, the force required would be sogreat that, should the material be tubing, it would collapse.

- Dallas U.S. Pat. No. 1,871,665 discloses a coiling machine in whichstrip material is bent prior to coiling, andin which the bending radiusis gradually increased. There is no disclosure of the formation ofconvolutions of constant radius of curvature, or of multi-layer coils.

Bram U.S. Pat. No. 3,195,338 shows a device for the continuous windingof wire in which single turn layers are built upwardly with the lastlayer always on the bottom of a coil. The building in an upward fashionof the multi-turn per layer of a multi-layer coil is not disclosed.

SUMMARY OF THE INVENTION The coil produced by the present method andapparatus is in the form of axially stacked pancake spirals calledradial layers, each radial layer'being a spiral of several concentricand coplanar convolutions. The radial layers are stacked axially inpartially nested relationship.

In making the coil, a strand of material such as tubing which retainsits shape when bent, is fed at constant speed to a bending stationhaving two or more pairs of guide rolls and a bending roll. The bendingroll is controlled by an electric and hydraulic network for impartingdifferent bending radii to the tubing passed tangentially by it.

In one embodiment, the bending roll bends at constant bending radiusenough material for making one complete coil convolution or turn. Thebending radius is then gradually changed such that each new convolutioneither just encircles or is just encircled by the previously madeconvolution. The bending radius is then held constant for one completeconvolution and then starts changing again at the same rate, but in adirection opposite to its most recent direction of change. The firstconstant radius convolution and the several immediately followingchanging radius convolutions define the first radial layer; the nextconstant radius convolution and the several following changing radiusconvolutions define the second radial layer, etc.

By rendering constant the bending radius during the making of aconvolution in a layer, it is believed that an additional length oftubing may be added to the layer, thereby, increasing the overall lengthof tubing making up a coil of given dimensions. Further, it is believedthat the constant bending radius facilitates the nesting of turns. v

Alternatively, constant radius convolutions bracketing changing radiusconvolutions may define a single radial layer. For example, the bendingroll may be held stationary during the making of two completeconvolutions, such that, in the finished coil, eachradial layer willconsist of an innermost and an outermost convolution having differentbut constant radii of curvature, and one or more intermediateconvolutions having varying radii of curvature.

Still further, the bending roll may be continuously reciprocating,without ever remaining stationary, such that no convolution is ofconstant radius of curvature.

The coil may be supported on 'a plurality of radial support rollers andmay be built upwardly, with newly bent tubing going on top of thesupport rollers but below the most recently coiled radial layer. Thecoil may alternatively be built downwardly, with newly bent tubing goingon top of the most recently made radial layer. Furthur, the coil may bebuilt in any direction.

In field use, the coil is unbent by passing the tubing through fixedlypositioned straightening rolls which remove the radius of curvature. Thecoil is supported on a spool supplied in the field and one free end ofthe coiled material may be passed through a guide secured in thevicinity of the axial periphery of the coil and then through thestraightening rolls. The free end is then pulled away and the coilbegins unwinding. As it does so, the radial layers separate, because ofthe presence of the guide, and when only a few radial layers are left,the whole remaining coil starts sliding toward the guide or toward theplane of the straightening rolls, should the guide be omitted. There isno need to move the coil spool axially as material is being unwound.

The advantage of this entire coiling-uncoiling arrangement is that thecoil is virtually self-contained, by virtue of the prebending, and iseasily unbent and uncoiled in the field.

BRIEF DESCRIPTION OF THE DRAWING FIG. 11 is a top view of apparatusembodying the invention, showing a bending station and a partiallycompleted supported layer of tubing.

FIG. 2 is a side elevational view of apparatus for uncoiling andzanbending.

FIG. 2a is a partial sectional view of the apparatus for uncoiling andunbending of FIG. 2, looking in the direction of arrows 2a.

FIG. 3 is a top view showing the bending station in greater detail.

FIG. 4 is a frontal, partly elevational and partly sectional view of thebending station looking in the direction of the arrows 4-4 of FIG. 3.

FIG. 5 is a side partly elevational and partly sectional view of adetail of the bending station looking in the direction of the arrows 5-5of FIG. -3.

FIG. 6 is a sectional view of a supported coil looking in the directionof the arrows 6-6 of FIG. 1.

FIG. 7 is a sectional view of a supported coil looking in the directionof the arrows 7-7 of FIG. 1.

FIG. 8 is a partly elevational and partly sectional view of a coil andof modified apparatus for. supporting it.

FIG. 9 is a schematic diagram of electrical apparatus associated withthe bending station.

FIG. 10 is a schematic representation of hydraulic and electricalapparatus associated with the bending station.

DETAILED DESCRIPTION The subject invention may be used in coiling anduncoiling any elongated material such as tubing, rod, wire, strip, etc.For thesake of brevity, however, reference will be made only to tubingas the material subjected to bending and unbending, it being understoodthat any other elongated material may be subjected to the sameprocessing or to processing within the scope of the invention.

THE con.

The coil produced by the present method and apparatus is made of acontinuous piece of tubing. The coil consists of a number ofpancake-like layers which are stacked. Each pancake layer is a spiralmade up of several concentric and coplanar convolutions of tubing. Thepancake-like layers are referred to herein as radial layers. A singleradial layer made up of convolutions a, 20b, 20c and 20d is visible inFIG. I. The coil as made is supported on rollers, so that it revolves asit is being formed. 1

Each convolution of tubing within a radial layer has a different radiusof curvature. In the making, a radial layer can be started either withthe innermost convolution, that is, the one with the smallest radius ofcurvature, or else with the outermost convolution, the one with thelargest radius of curvature, or else with any intermediate convolution.A coil which is started with an end convolution, say the outermostconvolution, will be described.

Suppose that a radial layer is started with the outermost convolution(20a in FIG. 1). A straight length of tubing equal to the circumferenceof the convolution 20a which is to be made is bent to the desired (e.g.,constant) radius of curvature. It should be noted here that thecurvature to which the tubing is being bent by bending apparatus isusually somewhat different from the curvature of the convolution whichfinally results, because the resiliency of the tubing tends tostraighten it somewhat after the bending force is removed.

Because of this difference, bending radius is used herein to mean theradius of curvature at which the tubing is bent, and radius of curvatureofa convolution is used to mean the radius of curvature of theconvolution after it has had a chance to straighten somewhat followingremoval of the bending force.

In making the coil, a length of material is bent, typically although notnecessarily at constant bending radius, and makes up a circularconvolution which is the outermost convolution 20a of the radial layervisible in FIG. 1. Following that, the bending radius is graduallydecreased such that the next convolution 20b will be just encircled bythe outermost convolution 20a. The bending radius is gradually decreasedstill more such that the next convolution 20c will be just encircled bythe previously made convolution 20b, and the next convolution 20d willbe just encircled by 20c.

The bending radius is then held constant during the making of the nextcomplete convolution following 20d. Thus at the end of the convolutionlabeled'20d and at the start of the next convolution a transition takesplace: one radial layer is completed and another one is started. Thetubing making the innermost convolution 20d of the completed layer nowgradually becomes the tubing making the innermost convolution 22d (seeFIG. 7) of a second radial layer which can be either above or below thefirst layer (below in FIG 7). Although a radial layer having only fourconvolutions is used as an example, it should be evident that any numberof intermediate convolutions may be made between the outermost andinnermost convolutions of a radial layer.

In the second layer, as seen in FIG. 7, the innermost convolution 22d ismade first, at constant bending radius, then another convolution 220 ismade at an increasing bending radius such that it just encircles theinnermost convolution 22d, then another convolution 22b which justencircles the previously made convolution 220, then another convolution22a which just encircles 22b. After the convolution 22a is completed,the bending radius is held constant and another transition takes placebetween tubing making the outermost convolution 22a of the second layerand tubing making the outermost convolution 23a of a third layer. Theconvolution 23a is made at constant bending radius.

The process as just described may continue until the coil has achievedthe desired size. As shown in FIG. 7, the coil is built upwardly; itcould just as well be built downwardly or in any other direction. Atanother cross section, however, the convolutions in one layer may bedirectly over the corresponding convolutions of the adjacent lowerradial layer and directly under the corresponding convolutions of theadjacent upper radial layer. Complete nesting is not possible because,as between two adjacent radial layers, one is in effect a lefthandspiral and the other one is in effect a right-hand spiral, and crossingover of convolutions must take place. Because of some shifting of radiallayers due to the weight of the coil, however, partial nesting ofconvolutions of one layer occurs between adjacent convolutions inadjacent layers.

In the coil described above it has been mentioned that constant radiusbending may be employed to produce turns (outermost and innermost) ofconstant radii of curvature. The utilization of constant bending radiusof outermost and innermost turns is desirable because it is believed toincrease the length of tubing that can be placed in a coil layer of agiven dimension over the length of tubing that may be acommodated withina layer of the same dimensions if the bending radius changescontinuously and is not held constant. However, it is feasible, ofcourse, to make a coil in which bending radius changes continuously(e.g., increasing then immediately decreasing then immediatelyincreasing, and so forth), so that the radius of curvature continuouslyvaries in the turns of all layers.

BENDING The apparatus for bendingand coiling is generally illustrated inFIG. 1, which shows tubing coming from the left-hand side of the drawingtoward a bending station 21.

The tubing may be supplied from standard forming and welding tube makingapparatus which takes up a coil of flat steel strip, bends it into along cylinder, welds the free edges, and partly shaves off the weldingbead for smooth circular cross-section. The tubing is forced out of suchapparatus atconstant speed.

Since the newly made tubing is forced toward the bending station 21, thecolumn strength of the tubing is usually sufficient for driving itthrough the bending station. Should the column strength of some tubingbe insufficient, appropriate auxiliary driving means (not shown) may beinstalled at or near the bending station 21'.

The bending station 21 has the job of bending the tubing 20 atappropriate bending radii for the making of the coil as previouslydescribed. In particular, the bending station 21 must bend the tubinglengths for making up different convolutions within a radial layer atdifferent bending radii, at least one of which is constant and the restof which gradually change as the tubing for particular convolutions arebeing bent. Alternatvely, the bending radius may continuously change.

After leaving the bending station, the newly bent tubing 20 is passedunder a support roller 85 which is a cylinder mounted for free rotationabout a horizontal axis, after which the tubing 20 passes over similarlymounted support rollers 89, 90, 86, 87 and 88. The tubing 20 then goesover the roller 85.

v The bending station 21, best seen in FIGS. 3, 4 and 5 has a rigidlysupported heavy base plate 28 over which an intermediate plate 29 ispivotally mounted. The pivot point is at a shaft 40 which extendsthrough the base plate 28 into an appropriate rigid support (notexpressly shown). Pivoting motion of the intermediate plate 29 iscarried out by means of a bolt 30 having one end pivotally attached to aspindle 301 secured to the top of the intermediate plate 29 and having athreaded shank which goes through a bore in the upstanding section of anL-shaped brace 31, the horizontal section of which is secured to thebase plate 28. Nuts 32 and 33 are threaded onto the shank of the bolt30, one on each side of the brace 31.

By loosening one of the nuts 32 and 33 and tightening the other, theintermediate plate 29 is caused to pivot about the shaft 40. Thepivoting of the intermediate plate 29 is for the purpose of initiallyadjusting the bending station to tubing of different diameters anddifferent elasticity characteristics. Once adjusted, the intermediateplate 29 would not normally change its position in relation to the baseplate 28 throughout a production run so long as the characteristics ofthe steel strip used to make the tubing remain reasonably constant.

The base plate 28 also supports two pairs of guide rolls: a pair made upof rolls 34 and 35 and a pair made up of rolls 36 and 37. The rolls arecoplanar and have peripheral grooves which cooperate to provide aconfining tangential passageway for the tubing 20. Different guide rollscan be used for different diameter or different shape tubing. Each ofthe guide rolls is mounted for free rotation on a shaft carried by asupport such as supports 38 visible in FIG. 4. Each of the supports 38has a bottom flange 381 which fits within guide rails 39 for slidingperpendicularly to the direction of feed of the tubing 20 foraccommodating different size tubing.

As best seen in FIG. 4, the shaft 40 extends through the base plate 28and upwardly through the intermediate plate 29 and has a sleeve 41fitted on it for free rotation immediately over the intermediate plate29. The inner diameter of the sleeve 41 is only slightly larger than theoutside diameter of the shaft 40. A horizontal pivot arm 42 extends fromthe sleeve 41 and carries a downwardly extending cylinder 43 having avertical cylindrical axis, and an upwardly extending shaft 44 along theaxis of the cylinder 43.

A sleeve 45 is also received on the shaft 40 similarly to the sleeve 41,but is positioned on top of the sleeve 41. The sleeve 45 carries atransverse arm 451 extending partially along the pivot arm 42. The arm451 is fixed at different positions relative to the pivot arm 42 bymeans of a bolt 46 threaded into an appropriately threaded bore of thesleeve 45 and having its head on the other side of an arcuate slot 47cut through the pivot arm 42. The are of the slot 47 has a radiuscentered at the shaft 40. The arm 451, extending from the sleeve 45 hasa groove 48 for accepting tangentially and directing the free end of thetubing 20 as it first appears in the feed direction.

The shaft 44 carries, above the pivot arm 42, a bending roll 49 fittedtightly for free rotation, above the shaft 44. The roll 49 has aperipheral groove similar to that of the guide rolls. Differently sizedbending rolls can be used for tubing of different sizes.

The cylinder 43 extending below the pivot arm 42 has at its bottomperiphery, as best seen in FIG. 5, a tongue 50 which carries fixedly anupwardly extending spindle 51. A cam follower wheel 52 is fitted tightlyover the spindle 51 for free rotation.

The periphery of the cam follower 52 is in the plane of the uniformlyslanted side of a horizontal wedge shaped linear cam plate 53 which isrigidly mounted on a shim block 54. The shim block 54 is in turn rigidlymounted on a guide plate 55. The guide plate 55 slides between guiderails 56 along the feed direction of the tubing 20. The guide rails arerigidly mounted on the intermediate plate 29.

For the purpose of moving the cam plate 53, the guide plate 55 isconnected to a shaft 57 which is parallel to the guide rails 56 andwhose other end is connected to the piston inside a hydraulic cylinder58. The cylinder 58 is a two-way device of standard design and can moveits piston,- and hence the guide plate 55 and the sam plate 53, ineither direction along the guide rails 56.

The cylinder 58 is mounted on the intermediate plate 29 by means ofbrackets 59, shim blocks 60 and bolts 61. Two hydraulic conduits 73 andwhich are shown only in FIG. 10 (schematically) go into the ends of thecylinder 58.

The intermediate plate 29 also supports electrical limit switches 62 and63 which have, respectively, pivoted arms 64 and 65, each carrying atthe free end a BENDING RADIUS CONTROL The operation of the hydrauliccylinder 58, and hence the movement of the cam plate 53 which changesthe bending radius by pivoting the bending roll 49, are controlled bythe electric and hydraulic networks illustrated schematically in FIGS. 9and 10.

FIG. 10 shows primarily the hydraulic controls. All elements indicatedthereon by reference numerals are of standard design; therefore, theyare shown only schematically. The arrow 67 indicates an incoming workingfluid conduit connected to a conventional source of fluid under pressuresufficient to move the piston inside the hydraulic cylinder 58. Thearrow 68 indicates the drainage hydraulic conduit which carries fluid toa storage tank at a lower pressure.

The incoming fluid goes into a standard four-way valve 69 which has twoworking fluid outlet conduits 70 and 71. The incoming flow over conduit67 can be selectively delivered into any one of the conduits 68, 70 and71.

The conduit 70 goes into a standard flow control and check valve 72, thepurpose of which is to allow, in one direction, full flow exceedingcertain pressure, for the purpose of driving a hydraulic piston, and toallow only partial flow in the opposite direction, for the purpose ofventing a hydraulic cylinder. A conduit 73 goes from the outlet of thecheck valve 72 into the left-hand side of the hydraulic cylinder'58. Theconduit 71 goes into a similar check valve 74 the outlet of which isconnected by means of conduit 75 to the right-hand side of the hydrauliccylinder 58.

Solenoids 76 and 77, of standard design, are operatively connected tothe four-way valve stroke. When neither of the solenoids 76 and 77 isenergized, the four-way valve 69 delivers the incoming fluid directly tothe drainage conduit 68 and there is no differential pressure on thepiston inside the hydraulic cylinder 58. When the solenoid76 isenergized, the four-way valve 69 delivers the fluid coming over theconduit 67 to the conduit 71, and the fluid eventually reaches therighthand side of the hydraulic cylinder 58, acts on the piston insideit, and causes the shaft 57 to move in an outward stroke. Fluid exhaustsfrom cylinder 58 through conduit 73, valve 72 and connected conduits 70,68 in valve 69. When the solenoid 77 is energized, the valve 69 connectsthe conduits 67 and 70, and the working fluid reaches the left-hand sideof the hydraulic cylinder 58 and causes the piston therein and the shaft57 to move in an inward stroke, Fluid exhausts through conduit 75, valve74 and connected conduits 71, 67 in valve 69.

The solenoids 76 and 77 are controlled by the electrical networkillustrated schematically in FIG. 9, in which the switches 62 and 63 arethe limit switches shown in FIG. 3, and solenoids 76 and 77 are the sameelements shown in FIG. 10.

FIG. 9 also shows two standard relays. One relay includes a fieldwinding 78 and contacts 78-1, 78-2 and 78-IT; the second relay includesa field winding 79 and contacts 79-1, 79-2A, 79-2B and 79-lT. The tworelays are identical in construction and in each, when the fieldwindings are deenergized, the contacts identified by the sufiix 1 areopen and the contacts identified by the suffix 2 are closed. When thefield windings are energized, the contacts identified by suffix l areclosed and the contacts identified by suffix 2 are open. The contacts78-IT and 79-1T are timed contacts; contacts 78-IT close at apredetermined'time after the energizing of winding 78 and opensimultaneously with the deenergization of that winding; contacts 79-ITclose at a predetermined time after the energizing of the winding 79 andopen simultaneously with the deenergization of that winding.

The circuit of FIG. 9 is connected to a suitable potential source, e.g.,110 volt A.C., and has a main off-on switch as well as an auxiliarystarting switch 81. The circuit operates in the following manner:

Assume that the main off-on switch 80 is closed at a time when limitswitches 62 and 63 are open. Starting switch 81 is manually closedmomentarily and current flows through the normally closed contacts 79-2Aand 78-2 and through the winding 79. The winding 79 is energized and thecontacts 79-1 close while the contacts 79-2A open. Winding 79 remainsenergized through now closed contacts 79-1 and normally closed contacts78-2.

With the energizing of the winding 79, the delay interval of the timedcontact 79-IT commences After the predetermined time delay, the timedcontacts 79-IT close, energizing the solenoid 77. The energization ofthe solenoid 77 causes working fluid to be delivered to the left-handside of the hydraulic cylinder 58, and the shaft 57 begins moving thecam plate 53 inwardly toward the right in FIGS. 10 and 3. The shaftmoves steadily until, as seen in FIG. 3, the striker plate 66 contactsand pivots the arm 65 of the limit switch 63, thus causing the limitswitch 63 to close and to energize the relay winding 78.

The energization of the relay winding 78 causes contacts 78-1 to closeand contacts 78-2 to open. The opening of the contacts 78-2 cuts off thecurrent through th relay winding 79 which in turn causes the contacts79-IT to open, deenergizing solenoid 77 and ceasing inward movement ofshaft 57. The closing of contacts 78-1, along with the now closedcontacts 79-2B, establishes a current path parallel to the switch 63which provides for continued energization of relay winding 78 regardlessof whether switch 63 is open or closed. The solenoid 76 is not yetenergized because of the time delay of the timed contacts 78-1'1. Atthis time there is no differential pressure in the hydraulic cylinder58, and the piston therein is stationary.

After its predetermined time delay, the contacts 78-IT close, causingthe solenoid 76 to be energized. This causes working fluid to bedirected to the righthand side of the hydraulic cylinder 58, and the camplate 53 begins moving outwardly, away from the hydraulic cylinder 58.The cam plate 53 moves steadily until the striker plate 66 contacts andpivots the arm 64 of the limit switch 62. The limit switch 62 is thusclosed, and the closing energizes the relay winding 79 which in turnopens the contacts 79-2B, cutting off the current through the relaywinding 78. The winding 79 remains energized through contacts 79-1 and78-2.

Relay winding 78 is now deenergized, which causes the opening ofcontacts 78-1' and 78-11, thus also deenergizing the solenoid 76. Bothsolenoids 76 and 77 are again deenergized; the cam plate 53 stays at itsoutermost position for the duration of the predetermined time delay ofthe contacts 79-1T. When the time delay is over, the solenoid 77 isenergized and the cam plate 53 begins moving inwardly toward thehydraulic cylinder 58.

The in and out movement of cam plate 53 described above is repeated foras long as the off-on switch 80 remains closed.

COIL SUPPORT The coil support mechanism is illustrated in FIGS. 1, 6 and7 which show a pair of stationary support beams 82 and 83 crossingorthogonally at the axis of the finished coil and held together byappropriate bracing structure generally indicated at 84. Each of thebeams 82 and 83 carries three cylindrical support rollers, two at oneend, and one at theother end. The beam 82 carries a support roller 85 atits end closest to the bending station 21, and support rollers 86 and 87at its other end; the beam 83 carries a support roller 88 at its endcloser to the bending station 21 and support rollers 89 and 90 at itsother end.

All support rollers are mountedon their respective beams for freerotation about their cylindrical axes by means of appropriate brackets91 whose bottom ends rest on a support. Additional brackets 92 areemployed for rotational support of the rollers 86 and 87 and the rollers89' and 98. In horizontal cross-section, the brackets 91 are outwardlyfacing channel sections. A vertical roller 91-a is attached for freerotationto each of the brackets 91, at the inside of the channel, forthe purpose of preventing the coil from slipping off the supportrollers.

As best seen in FIGS. 6 and 7, the support rollers are mounted indifferent horizontal planes. The roller 85 is at the highest level, theroller 88 is at the next lower level, the rollers 86 and 87 are in acommon plane and at the next lower level, and the rollers 89 and 90 arein a common plane at the lowest level. The support rollers carry themost recently bent radial layer of tubing, since the coil is pushedupwardly as it is built.

An alternative supporting mechanismis illustrated in FIG. 8 which showsa basket 93 which supports at its bottom the first made radial layer oftubing. The basket 93 has, at its bottom, lockable coasters 94 of whichonly two are shown. The coasters 94 rest on a flat circular plate 95having a smaller concentric ring 96 attached to its bottom.

The ring 96 rests upon a roller bearing 96a appropriately supported by atop flange 97 of a heavy shaft 98, so that the plate 95 can rotate asbent tubing is deposited in the basket 93. The shaft 98 extends upwardlyfrom the piston of a heavy underground hydraulic cylinder 99. A circulardepression 100, slightly larger in diameter than the plate 95, is cutinto the ground surface 101 to accommodate the plate 95 when it isbrought, by the action of the hydraulic cylinder 99, to the groundlevel. The top of the plate 95 is thus flush with the ground surface101, and the basket 93 can be rolled away on the coasters 94, afterunlocking the coasters.

coluNo An example will be given now of producing a coil formed of threeradial layers;

Tubing 20 is fed toward the bending station 21. The free end of thetubing is inserted between the opposing guide rolls 34 and 35, and thenbetween the guide rolls 36 and 37. The free end of the tubing 20 nextstrikes tangentially the groove 48 of the arm 451 visible in FIG. 4 andthen goes tangentially into the peripheral groove of the bending roll'49.

Assume that both solenoids 76 and 77 are deenergized, that the cam plate53 has just reached the position closest to the hydraulic cylinder 58and that the time delay interval of timed contacts 78-1T has justcommenced.

Since solenoids 76 and 77 are deenergized, there is no differentialpressure on the piston inside the hydraulic cylinder 58, and the camplate 53 is stationary. As the tubing 20 is fed past the bending roll49, it is bent at a constant bending radius. The intermediate plate 29has been pivoted about the shaft 40 by means of bolt 30 and nuts 32 and33 suchthat the bending radius at this position of the cam plate 53results in the desired radius of curvature of the outermost convolutionof the coil that is to be made.

The tubing 20 thus proceedstangentially past the bending roll 49 and isbent at a constant bending radius for as long as necessary to bend' thelength of tubing required for the outermost coil convolution 20a. Thislength of time is defined by the predetermined time delay of the timedcontacts 78-1T.

As the free end of the tubing 20 moves away from the bending roll 49, itis first passed under the support roller 85. When the free end reachessupport roller 89, it is passed over it, and then over support rollers90, 86, 87 and 88. When the free end of the tubing 20 again reaches theroller 85, it is passed over it and goes over the roller at everysubsequent convolution. The tubing coming from the bending station 21,however, always passes first under the roller 85.

As soon as the delay interval of the contacts 78-1T is over theconvolution 20a, as shown in FIGS. 1, 6 and 7 has been made and thesolenoids 76 is energized. Uniform fluid flow is now delivered to theright-hand side of the hydraulic cylinder 58 and the cam plate 53 beginsmoving outwardly, away from the hydraulic cylinder 58, at a steady rateand begins changing the bending radius. The taper of the cam plate 53and its rate of motion are such that the change of bending radius willresult in changes of radii of curvature of the completed convolutionsnecessary to nestle each convolution of the radial layerthat is beingmade inside the previously made convolution. Different cam plates may beused for tubing of different diameters or of different metals.

As the final convolution 20d of the first radial layer is completed, thestriker plate 66 contacts the limit switch 62, closes it, and thuscauses the solenoids 76 to be deenergized, thereby stopping outwardmovement of the cam plate 53. The time delay interval of timed contacts79-1T is initiated-as described above. The time delay of the contacts79-1T is set such that one complete convolution is made 'at a constantbending radius.

At the time of starting the constant bending radius period (thebeginning of the time delay interval), a

transition takes place between the first radial layer and the secondradial layer. 4

The convolution 20d of the first radial layer is made at a steadilydecreasing bending radius and nestles inside the previously madeconvolution 20c, as noted above, but the next convolution, theconvolution 22d, is bent at a constant bending radius and cannot nestleinside the convolution 20d. Since the tubing for making the convolution22d is coming from under the support roller 85, and cannot fit insidethe circle of the convolution 20d, it pushes up the convolution 20d andfits under it, remaining somewhat offset toward the center of the coil.The second radial layer is thus begun by the tubing for the convolution22d going under (pushing up) the first radial layer.

As soon as the delay interval of the timed contacts 79-1T is over, thesolenoid 77 is energized and the cam plate 53 begins moving inwardly,toward the hydraulic cylinder 58 and decreases gradually and uniformlythe bending radius. The second radial layer continues being built bytubing 20 coming from underneath the roller 85 and being pushed betweenthe first radial layer and the rollers 89 and 90. While the first radiallayer was built from the outermost convolution inwardly toward itsinnermost convolution, the second radial layer is built outwardly fromits innermost convolution.

The making of the second layer continues through the time the strikerplate 66 reaches the-limit switch 63.

Then, after the completion of the convolution 22a, the

solenoid 77 is deenergized and the movement of the cam plate 53 stops.The time delay interval of the contact 78-1T now begins, and the camplate is stationary for a time interval sufficient to make one completecoil convolution (23a).

At or about the time the constant radius convolution is started, anothertransition takes place, this time a transition between the second radiallayer and the third radial layer.

When the convolution 23a is started, it cannot encircle the previouslymade convolution 22a. The radius of curviture of convolution 23a doesnot increase, because the bending radius for convolution 23a is heldconstant. Thus, the newly bent tubing for the convolution 230 forcesitself under the convolution 22a and a little to the outside of it, asbest seen in FIG. 7.

When the predetermined delay interval of the timed contact 78-1T is over(completion of convolution 230), the solenoid 76 is again energized andthe cam plate 53 begins moving outwardly, away from the hydrauliccylinder 58. The third radial layer is now being made of tubing beingpushed under the support roller 85 and between the second layer and thesupport rollers 89 and 90 to make convolutions 23b, 23c and 23d.

The process described above is repeated until the desired number ofradial layers has been formed.

In the coiling process just described, in each radial layer oneconvolution is bent at a constant bending radius and the remainingconvolutions are bent at constantly decreasing or constantly increasingbending radii. It is possible, however, to produce a coil by bendingboth the outermost and the innermost convolutions of each radial layerat two different but constant bending radii and bending any intermediateconvolutions within a radial layer at either decreasing or increasingbending radii. This modification can be accomplished simply by adjustingthe time delays of contacts 78-11 and 79-1T of FIG. 9 such that the cam53 stops at each of its extreme positions for a time interval longenough for making two (or even more) complete convolutions.

Alternatively, the timed contacts 78-1T and 79-lT may be adjusted tozero delay, or relays which have no timed contacts may be employed, soas to make the cam 53 reciprocate without stopping at either extreme ofits movement. The resulting coil will be composed of convolutions all ofwhich have a varying radius of curvature. 1

Further, the cam plate may be contoured nonlinearly so as to varynon-linearly the bending radius.

When the alternative support mechanism illustrated in FIG. 8 is used,the only major difference is that the coil is being built downwardlyinstead of upwardly. As bent tubing leaves the bending roll 49, it firstgoes onto the bottom of the basket 93 which is positioned at that timejust below the horizontal level of the bending roll 49. As the build-upof radial layers progresses, the basket 93 is dropped further andfurther downwardly by controlling the pressure inside the hydrauliccylinder 99 through conventional means.

When the desired number of radial layers is completed, the top of thesupport plate 95 is brought flush with the ground surface 101 and thebasket 93 is rolled away on its coasters 94 to a site for furtherprocessing of the coil.

It should be noted that when a coil is built upwardly (each layer goingbeneath the previously formed layer) the length of material emergingfrom the bending station takes a large portion of the entire weight ofthe coil thereabove, since the coil is being raised upwardly as it isbeing built. 0n the other hand, for a coil being built downwardly (eachlayer going above the previously formed layer) no raising of the coil isinvolved. Hence in this latter case each turn in the coil only takes theweight of the turns directly thereabove. As a result, larger sized coilscan be built downwardly rather than upwardly. The advantage gained bybuilding a coil upwardly is that significant space beneath the bendingstation need not be taken. In some environments, space beneath a bendingstation may not be available, necessitating the upward building ofcoils.

Steel tubing has been coiled in accordance with the invention. Forexample, steel tubing of 2 inches outside diameter and a wall thicknessof 0.072 inch has been coiled typically about 700 feet of tubing makingup a single coil. The coil has been formed with radial layers of aboutfour turns or convolutions per layer, each layer having an outsidediameter of about inches and an inside diameter of about 60 inches. Thecoils formed were about 3 feet in height (about 10 radial layers) andbuilt upwardly, i.e., each layer as produced was positioned beneath thelayer previously produced. The length of tubing in a single layer of thecoil depended upon whether the layer was formed with a turn of constantbending radius on the inside or the outside of the layer. For example,those layers having turns of constant radius of curvature on the insideof the coil included about 60 feet of tubing per layer, while thoselayers having turns of constant radius of curvature at the outside ofthe coil included about 78 feet of tubing per layer. The effect onlength of tubing in a layer by maintaining bending radius constant isshown by these different lengths of tubing per layer. Coils so producedhave been wrapped with cardboard and strapped with about three strapsfor shipment.

UNCOILING After a coil is produced as described heretofore, it may besubjected to further processing such as coating with plastic, testingfor strength and continuity, wrapping, etc.

When the time comes to use tubing from the coil, such as for example ingas main laying, the tubing must be straightened by removing the radiusof curvature of each convolution. Otherwise, uncoiled tubing wouldspring back to its coiled form if not restrained.

One example of apparatus for straightening coiled tubing is shown inFIGS 2 and 2a.

FIG. 2 shows a part of a land vehicle 102 which may be a standard pipelaying rig carrying at its rear end a plow 103. The plow 103 is slidablymounted and can be raised to clear the ground surface or lowered to plowat a suitable depth by the use of mechanisms well known in the field ofgas main laying. A pair of parallel beams 104 (only one shown) ispivotally attached to the plow at a pivot shaft 105 and extends awayfrom it at a 30 to 45 angle from the horizontal. The beams support forfree rotation a removable spool 106 mounted on an axle 1061perpendicular to the beams 104 and received into appropriate borestherein.

A pair of hydraulic cylinders 107 (only one shown) extends, one from thelower portion of each beam 104, to a support 100 carried by the vehicle102. The cylinders 107 are two-way devices and can raise or lower thebeams 104 and the spool 106 carries a coil 109 wound in accordance withthe preceding description.

As seen in FIG. 2a, an arm 110 extends from the free end of the beam 104toward the other beam 104, and a shaft 111 carrying at its free end aperipherally grooved guide roll 112, extends from the free end of thearm 110 toward the axis of the spool 106.

The free end of the coiled tubing is passed between beam 104 shown inFIG. 2a and the guide roll 112, tangentially to the groove of theroll112, such that the tubing fits into the groove of the guide roll. Thefree end is then passed between opposing guide rolls 113 and 114,tangentially to the grooves of guide rolls 115 and 1 16 and through thepassageway between straightening rolls 117, 118 and 119. The guide rolls113 through 116 and straightening rolls 117, 118 and 119 are mountedrotatably in the plow 103.

The free end of the tubing is pulled through its path past the guiderolls by means of a cable 120 and a suitable gripping device 121. Thestraightening rolls 117, l 18 and 1 19 are disposed in a triangularpattern appropriate for substantially removing the radius of curvatureof the tubing passed between them. The straightto retention by the guideroll 112 of the convolution which is being straightened. When only a fewradial layers are left in the coil, the whole coil may begin slidingtoward the guide roll 112. There is no need at any time for axialmovement of the spool 106.

The guide roll 112 may be omitted and one of the free ends of the coil109 may be fed directly to the guide rolls 113, 114, and 116 and then tothe straightening rolls 117,118 and 119.

We claim:

1. A coil of continuous elongated material compris ing a plurality ofaxially stacked radial layers, each radial layer comprising a pluralityof coplanar convolutions, each convolution within each radial layerbeing continuous with each immediately adjacent convolution of thatradial layer, each convolution being prebent prior to coiling, whereinthe length of material making up at least one of the outermost andinnermost convolutions in each of a plurality of layers is prebent to aconstant radius of curvature, and wherein the length of material makingup at least one of the convolutions in that layer between the outermostand innermost convolutions is prebent to a non-constant radius ofcurvature.

2. A coil as defined in claim 1 wherein, within a radial layer, thelength of material making up only one of the innermost and outermostconvolutions is prebent to a constant radius of curvature.

3. A coil as defined in claim 1 wherein, within a radial layer, thelengths of material making up the innermost and the outermostconvolutions are prebent to different but constant radii of curvature.

4. A coil as defined in claim 1 wherein, in each pair of axiallyadjacent radial layers, the two convolutions that are continuous witheach other are prebent such that one is prebent to a constant radius ofcurvature while the other is prebent to a non-constant radius ofcurvature.

5. A coil as defined in claim 1 wherein one of the outermost andinnermost convolutions of each radial layer, except the end layers, issubstantially nested inside the adjacent outermost or innermostconvolutions,

as the case may be, of the two adjacent radial layers.

1. A coil of continuous elongated material comprising a plurality ofaxially stacked radial layers, each radial layer comprising a pluralityof coplanar convolutions, each convolution within each radial layerbeing continuous with each immediately adjacent convolution of thatradial layer, each convolution being prebent prior to coiling, whereinthe length of material making up at least one of the outermost andinnermost convolutions in each of a plurality of layers is prebent to aconstant radius of curvature, and wherein the length of material makingup at least one of the convolutions in that layer between the outermostand innermost convolutions is prebent to a non-constant radius ofcurvature.
 2. A coil as defined in claim 1 wherein, within a radiallayer, the length of material making up only one of the innermost andoutermost convolutions is prebent to a constant radius of curvature. 3.A coil as defined in claim 1 wherein, within a radial layer, the lengthsof material making up the innermost and the outermost convolutions areprebent to different but constant radii of curvature.
 4. A coil asdefined in claim 1 wherein, in each pair of axially adjacent radiallayers, the two convolutions that are continuous with each other areprebent such that one is prebent to a constant radius of curvature whilethe other is prebent to a non-constant radius of curvature.
 5. A coil asdefined in claim 1 wherein one of the outermost and innermostconvolutions of each radial layer, except the end layers, issubstantially nested inside the adjacent outermost or innermostconvolutions, as the case may be, of the two adjacent radial layers.